Coating compositions for application to floor tiles and other flooring to provide a no-wax finish are well known. Two examples of oligomers used in such coatings are the UVITHANE 783 and 788 oligomers available from the Specialty Chemicals Division of Thiokol Corporation, Trenton, New Jersey. (UVITHANE is a registered trademark).
Because the particular oligomers useful for flooring coatings are frequently very viscous or solid at the preferred application temperature, reactive diluents are frequently added to the compositions to improve their handling characteristics. (As used here, the term "reactive diluent" refers to an ethylenically unsaturated monomer which is miscible with the principal oligomer, reduces the viscosity of the composition when it is added to the oligomer, and reacts with the oligomer to form a copolymer when the composition is cured by exposure to ultraviolet light or other actinic radiation. A reactive diluent is different from a conventional solvent because it participates in the reaction, rather than evaporating or remaining as a diluent in the cured coating.) One conventional reactive diluent for flooring compositions is N-vinyl pyrrolidone: ##STR2## The use of reactive diluents in general is disclosed in columns 8-9 and 26-27 of U.S. Pat. No. 3,924,023, issued to Boranian et al. on Dec. 2, 1975, and in U.S. Pat. No. 4,287,323, issued to Tefertiller et al. on Sep. 1, 1981 (particularly in column 6).
The choice of reactive diluent will affect the physical characteristics of the acrylate coating and film. In addition to imparting good physical properties (such as elongation) to the cured film, the reactive diluent should have low volatility in the uncured coating and a rapid cure rate.
Several prior inventors have disclosed certain species of: ##STR3## wherein R.sup.1 is a monovalent aromatic or alkyl radical including from about 4 to about 20 carbon atoms, R.sup.2 is a divalent alkyl radical including from about 2 to about 4 carbon atoms, and R.sup.3 is hydrogen or methyl. Structures of this type are disclosed in U.S. Pat. No. 3,479,328, issued to Nordstrom on Nov. 18, 1969.
Other patents which may have some relevance in connection with this invention are U.S. Pat. No. 3,553,174, issued to Hausslein on Jan. 5, 1971; U.S. Pat. No. 3,645,977, issued to Wolgemuth et al. on Feb. 29, 1972; U.S. Pat. No. 3,783,151, issued to Carlick et al. on Jan. 1, 1974; and U.S. Pat. No. 4,279,833, issued to Culbertson, et al. on July 21, 1981. Of these patents, Nordstrom, Boranian, Culbertson, and Tefertiller, et al. teach coatings for flooring materials. However, the prior art has not disclosed the materials described and claimed herein as reactive diluents for ultraviolet curable flooring